Some of the usual situations for the Venice tourist:

Galleria degli CavalliAdmiring the view from San Marco's Balcony...

View from the bell tower... or wandering through the San Marco Square

Maybe feeding the pidgeons:
 
Pidgeons Pidgeons Pidgeons

Even outside the Carnival time tourists will spend a lot of time (and money) at masks shops or hats sellers.
 
Mask shop Hats Mask shop

But a crowd like this, I am sure you will see only during the Carnival:
 
Sunset Crowd